The present invention relates to a device for storing and/or mixing and/or injecting cements, especially bone cements.
Many of the present-day cements, which are produced from two components, a powdery component and a liquid component, polymerize after the components are mixed thoroughly and subsequently form a hard and more or less permanent cement composition. Aside from the polymerizable cements, so-called hydraulic cements, such as phosphate cements, may also be used.
Polymethacrylates, which are also referred to as PMMA, are most frequently used as bone cements at the present time. PMMA include a powdery polymer and a liquid monomer. When mixed, these components polymerize within minutes and form a firm connection between the prosthesis and the bone structure surrounding the prosthesis.
In addition, calcium phosphate cements are also increasingly used at the present time. Here also, a powdery component is mixed with a liquid component. After the components are mixed, the cement is hardened by a precipitation reaction.
Devices for mixing and metering pharmaceutical products are known. For example, German Patent No. DE 297 21 534 discloses a mixing and metering container which comprises a container body, which includes an internal cylindrical space having an outlet with a tapering diameter at one end and a piston unit at the other end of the container body. The piston unit seals the end of the container body and is axially movable in the internal cylindrical space. The piston unit has an opening for receiving a drive shaft of a mixing tool, which can be driven into the internal cylindrical space. The container also includes a driving device, which engages the opening and is connected to the container body. However, the driving device can only be connected to the container body after the mixing tool is removed. The piston unit is moved by a threaded rod, the threaded rod being actuated manually by an actuating element at the end of the driving device. It is a disadvantage of this known device that an adequate distance between the mixing tool and the wall of the mixing space is not necessarily ensured so that, when abrasive powders are mixed, there may be appreciable wear on the mixing tool and/or on the wall of the mixing space, the abraded particles having a negative effect on the quality of the product.